Hamas intended the civilian deaths as an end when they attacked. They wanted to cause outrage by killing families in their homes.
Israel intends to destroy Hamas, and the civilian deaths are not-intended as an end. Israel knows that outrage is detrimental to itself. They just weren't willing to let Hamas use its civilian population as a shield...but they weren't trying to destroy the shield (as we can see with so many survivors), but instead were trying to destroy the shield bearer (Hamas).